HOUSTON -- The frustration continues to mount for injured rookie outfielder George Springer, who took to cracking a joke about being more concerned about the sore thumbs of outfielder Jake Marisnick than he is about his own health.

It's still unclear when Springer will be activated from the disabled list. He returned Thursday from a three-game rehab stint at Class A Quad Cities in which he tweaked his strained left quad running the bases and suffered a setback.

"I want to play," he said. "It's tough to just sit here. Your health is obviously more important. I've got to show that I can get healthy and hopefully get back out there."

Springer is taking batting practice, but he said the issue at this point is making sure he won't reinjure the quad when he gets to game speed, which can't be simulated. Thus, he's taking it slow.

"I have to be smart about it," he said.

Springer said he didn't know if he would have to be sent back out on another Minor League rehab assignment to prove he's healthy enough to play at the Major League level.

"If that's what it takes to make sure I'm OK, that's what I'll have to do," he said.

"He has some discomfort and we're just going to have to weigh all the options and just continue to monitor him as we move forward," he said. "Let him continue with the course in which the trainers are taking, and if this becomes something of more length, we'll revisit [a Minor League rehab assignment] at that time."